001: /*BEGIN_COPYRIGHT_BLOCK
002: *
003: * Copyright (c) 2001-2007, JavaPLT group at Rice University (javaplt@rice.edu)
004: * All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions are met:
008: * * Redistributions of source code must retain the above copyright
009: * notice, this list of conditions and the following disclaimer.
010: * * Redistributions in binary form must reproduce the above copyright
011: * notice, this list of conditions and the following disclaimer in the
012: * documentation and/or other materials provided with the distribution.
013: * * Neither the names of DrJava, the JavaPLT group, Rice University, nor the
014: * names of its contributors may be used to endorse or promote products
015: * derived from this software without specific prior written permission.
016: *
017: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
018: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
019: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
020: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
021: * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
022: * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
023: * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
024: * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
025: * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
026: * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
027: * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
028: *
029: * This software is Open Source Initiative approved Open Source Software.
030: * Open Source Initative Approved is a trademark of the Open Source Initiative.
031: *
032: * This file is part of DrJava. Download the current version of this project
033: * from http://www.drjava.org/ or http://sourceforge.net/projects/drjava/
034: *
035: * END_COPYRIGHT_BLOCK*/
036:
037: package edu.rice.cs.util;
038:
039: import java.util.*;
040:
041: public class BidirectionalHashMap<Type1, Type2> {
042: HashMap<Type1, Type2> forward = new HashMap<Type1, Type2>();
043: HashMap<Type2, Type1> backward = new HashMap<Type2, Type1>();
044:
045: public void put(Type1 key, Type2 value) {
046: if (forward.containsKey(key)) {
047: throw new IllegalArgumentException("Key " + key
048: + " exists in hash already.");
049: }
050: if (forward.containsValue(value)) {
051: throw new IllegalArgumentException(
052: "Double hashes must be one to one. " + value
053: + " exists already in hash.");
054: }
055: forward.put(key, value);
056: backward.put(value, key);
057: }
058:
059: public Type2 getValue(Type1 key) {
060: return forward.get(key);
061: }
062:
063: public Type1 getKey(Type2 value) {
064: return backward.get(value);
065: }
066:
067: public boolean containsKey(Type1 key) {
068: return forward.containsKey(key);
069: }
070:
071: public boolean containsValue(Type2 value) {
072: return backward.containsKey(value);
073: }
074:
075: public Iterator<Type2> valuesIterator() {
076: return new BHMIterator();
077: }
078:
079: public boolean isEmpty() {
080: return forward.isEmpty();
081: }
082:
083: /** Returns a Collection<Type2> in some order. */
084: public Collection<Type2> values() {
085: return forward.values();
086: }
087:
088: public Object[] valuesArray() {
089: return values().toArray();
090: } // Return type should be Type2[]; type erasure bites!
091:
092: public Type2[] valuesArray(Type2[] a) {
093: return values().toArray(a);
094: } // argument is hack to get the return type right
095:
096: public Type2 removeValue(Type1 key) {
097: Type2 tmp = forward.remove(key);
098: backward.remove(tmp);
099: return tmp;
100: }
101:
102: public Type1 removeKey(Type2 value) {
103: Type1 tmp = backward.remove(value);
104: forward.remove(tmp);
105: return tmp;
106: }
107:
108: public int size() {
109: return forward.size();
110: }
111:
112: public void clear() {
113: forward = new HashMap<Type1, Type2>();
114: backward = new HashMap<Type2, Type1>();
115: }
116:
117: public String toString() {
118: String ret = "";
119: ret = "forward = " + forward.values() + "\nbackward = "
120: + backward.values();
121: return ret;
122: }
123:
124: /** Iterator class for BiDirectionalHashMap */
125: class BHMIterator implements Iterator<Type2> {
126:
127: Iterator<Type2> forwardIt = forward.values().iterator();
128:
129: /** Cached value of last element returned by next() */
130: Type2 lastValue = null;
131:
132: public boolean hasNext() {
133: return forwardIt.hasNext();
134: }
135:
136: public Type2 next() {
137: lastValue = forwardIt.next();
138: return lastValue;
139: }
140:
141: /** Removes last element returned by next(); throws IllegalStateException if no such element */
142: public void remove() {
143: forwardIt.remove(); /* throws exception if lastValue is null */
144: backward.remove(lastValue); /* cannot fail because lastValue is not null */
145: lastValue = null;
146: }
147: }
148: }
|